Has Anyone Ever Tried Modelling a Battery Cover?
It seems like your asking for some help adding the 3d parts of this model. 


  I know for the top 2 extruding parts that I'll need to be like the part of other battery covers that have that dip in the middle. As for the bottom 4 smaller extruding parts, I think they'll need some sort of hook on the ends.


This can be done many ways. You may already be familiar with some of them. The most effective would probably be edit mode in blender. You should look into "proportional editing" and "boolean modifiers".

I would model the tabs as a 2d face side profile and extrude them. You could then use an array and boolean modifier to make the final mesh.